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A subset of patients with metastatic renal cell carcinoma (mRCC) follow an indolent disease course and may benefit from initial active surveillance (AS). However, selecting patients suitable for this approach is challenging. To investigate this we sought to define outcomes of patients with mRCC suitable for initial AS. All patients with mRCC clinically selected for initial AS at the Edinburgh Cancer Centre between January 2010 and December 2020 were identified. Key inflammatory biomarkers (haemoglobin, white cell count, neutrophil count, platelets, C-reactive protein [CRP], albumin, corrected calcium) and the International Metastatic RCC Database Consortium (IMDC) risk score were measured. The relationship between these and time to systemic anticancer therapy (tSACT) and overall survival (OS) was analysed. Data were available for 160 patients. Estimated median overall survival was 88.0 (interquartile range [IQR] 34.0-127.0) months. Median tSACT was 31.8 (IQR 12.0-76.3) months. On multivariate analysis, only CRP was predictive of tSACT (HR 2.47 [95% CI:1.59-3.85] p 0.001) and OS (HR 3.89 [95% CI:2.15-6.83] p 0.001). Patients with CRP 10 mg/L were more likely to commence SACT within 1 year than those with CRP≤10 mg/L (41% vs. 18%, Relative Risk 2.16 (95% CI:1.18-3.96) (p = 0.012)). IMDC risk score was not predictive of tSACT or OS. Active surveillance is an appropriate initial management option for selected patients with mRCC. CRP, a biomarker of systemic inflammation, may provide additional objective information to assist clinical decision-making in patients with mRCC being considered for initial AS. Although this is a retrospective observational study, the cohort is well defined and includes all patients managed with initial AS in an inclusive real-world setting.

Testicular cancer is the most common malignancy in young men. We discuss four cases of germ cell tumours (GCTs) presenting to general practitioners and physicians where there were notable preventable delays in the diagnosis and management. This diagnostic delay is associated with a more advanced stage of disease, and subsequent increased treatment-related morbidity and decreased survival. Our series highlights the variety of ways in which GCTs may present and we discuss the importance of prompt diagnosis through a thorough history and examination, early measurement of serum tumour markers and appropriate multidisciplinary team discussion. GCTs are highly curable cancers in the majority of patients and delays in management can, therefore, have devastating consequences.

Surgery for renal cell carcinoma (RCC) with venous tumour thrombus (VTT) extension into the renal vein (RV) and/or inferior vena cava (IVC) has high peri-surgical morbidity/mortality. NAXIVA assessed the response of VTT to axitinib, a potent tyrosine kinase inhibitor.NAXIVA was a single-arm, multi-centre, Phase 2 study. In total, 20 patients with resectable clear cell RCC and VTT received upto 8 weeks of pre-surgical axitinib. The primary endpoint was percentage of evaluable patients with VTT improvement by Mayo level on MRI. Secondary endpoints were percentage change in surgical approach and VTT length, response rate (RECISTv1.1) and surgical morbidity.In all, 35% (7/20) patients with VTT had a reduction in Mayo level with axitinib: 37.5% (6/16) with IVC VTT and 25% (1/4) with RV-only VTT. No patients had an increase in Mayo level. In total, 75% (15/20) of patients had a reduction in VTT length. Overall, 41.2% (7/17) of patients who underwent surgery had less invasive surgery than originally planned. Non-responders exhibited lower baseline microvessel density (CD31), higher Ki67 and exhausted or regulatory T-cell phenotype.NAXIVA provides the first Level II evidence that axitinib downstages VTT in a significant proportion of patients leading to reduction in the extent of surgery.NCT03494816.

645 Background: The Keynote 426 trial demonstrated 3-weekly pembrolizumab 200mg (pem3w) plus axi twice daily is effective in aRCC. We previously reported real-world experience of pem6w + axi demonstrating a comparable safety profile to pem3w + axi reported in Keynote 426, with the added benefit of less frequent hospital visits. Here we present updated results on progression free survival (PFS) and landmark analyses of overall survival (OS) at 6, 9 and 12-months. Methods: Electronic medical records of pts on pem6w + axi between 1st May 2020 & 1st June 2021 in two large cancer centres in Scotland were analysed retrospectively for pts’ characteristics, efficacy and treatment related adverse events (TRAE). A data cut-off of 1st June 2022 was applied. Results: A total of 93 pts were identified (baseline demographics previously reported). 74 pts (80%) had clear cell histology, 19 pts (20%) had non-clear cell and 11 pts (12%) had sarcomatoid component. Approximately half had previous nephrectomy (46 pts). 15 (16%), 46 (50%) and 32 (34%) pts respectively were classified as favourable, intermediate, and poor risk group as per international metastatic renal cell carcinoma database consortium (IMDC) criteria. The median follow-up was 13 months (inter-quartile range [IQR] 8-17). At data cut off, 59 (63%) had progressed or died, with median PFS of 10.7 (IQR: 4.6-not reached) months. At landmark time-points of 6, 9 and 12 months 63 (68%), 50 (54%) and 42 (45%) of pts were progression free (Table). The median OS was not reached and follow up continues. At landmark time-points of 6, 9 and 12 months 88 (95%), 69 (74%) and 65 (70%) of pts were alive (Table). Clinician assessed radiological response was evaluable in 87 pts. Overall response rate (ORR), including partial response and complete response, was noted in 51 pts (59%). Clinical benefit rate including pts with ORR and stable disease was seen in 74 pts (85%). 82 pts (88%) had any grade and 28 pts (30%) had grade 3/4 TRAE. Any grade immune related AE (irAE) occurred in 62 pts (67%) and grade 3/4 in 19 pts (20%); g3/4 transaminitis (10%), colitis (8%), nephritis (2%) and skin (2%). Any grade AE due to axi occurred in 69 (74%) and grade 3/4 AE in 14 pts (15%). 25pts (27%) on Pem and 19pts (20%) on axi discontinued treatment due to TRAE. Conclusions: Our real-world experience demonstrates that pem6w + axi appears to have comparable efficacy and safety profile to pem3w + axi reported in Keynote 426 study. [Table: see text]

716 Background: CRP, a biomarker of systemic inflammation, has been shown to have prognostic value in numerous tumour types, including mRCC. The combination of the immune check inhibitor (ICI), pembro, and vascular endothelial growth factor receptor tyrosine kinase inhibitor (VEGFR-TKI) axi is one of several internationally approved combination ICI/VEGFR-TKI treatment options. We evaluated the predictive value of biomarkers of systemic inflammation in a real-world cohort of patients with mRCC treated with pembro and axi. Methods: Retrospective data of patients treated with pembro and axi were collected from a regional electronic database from two large cancer centres. Inflammatory biomarkers from routine blood tests (including haemoglobin, neutrophil count, platelets, albumin and CRP) prior to starting treatment were recorded. The IMDC score and modified Glasgow Prognostic Score (combining albumin and CRP) were calculated. The primary end point, progression free survival (PFS), was defined as the time between initiation of treatment and clinical or radiographical progression or death, or censorship. Overall survival, defined as the time between initiation of treatment and death, or censorship was also calculated. Univariate and multivariate analyses were undertaken using Cox Regression model and the relationship between different markers and PFS was assessed using Kaplan-Meier curves. Results: Data were available for 93 patients. 74 pts (80%) had clear cell histology, 19 pts (20%) had non-clear cell and 11 pts (12%) had sarcomatoid component. 46 patients had previous nephrectomy. 15 (16%), 46 (50%) and 32 (34%) pts respectively were classified as favourable, intermediate, and poor risk group as per IMDC score. Median PFS was 10.7 (IQR 4.6-not reached) months after a minimum 12.5 months follow-up. Baseline CRP was recorded in 77 (83%) patients, reflecting current routine clinical guidelines. On univariate analysis, neutrophils (≤7.5x109/L/>7.5x109/L) (p=0.044), platelets (≤400 x109/L/>400x109/L) (p=0.043), CRP (≤10mg/L/>10mg/L) (p=0.001), mGPS (0/1/2) (p=0.004) and IMDC risk group (low/intermediate/poor) (p=0.038) were predictive of PFS. On multivariate analyses only CRP was associated with PFS (HR2.78 (95% CI, 1.42-5.44) (p=0.003). At a 1-year landmark PFS was 62% (CRP ≤10mg/L) v 29% (CRP >10mg/L) (p=0.002). CRP also predicted OS ((HR4.50 (95% CI, 1.58-12.8) (p=0.005)) with 1-year OS 85% (CRP ≤10mg/L) v 59% (CRP >10mg/L) (p=0.002). Conclusions: CRP, a biomarker of systemic inflammation, predicts survival in mRCC patients undergoing combined ICI/VEGF-TKI therapy. Our findings support comparable studies in the mRCC population and routine recording of CRP in patients with mRCC. We advocate further work to validate utilisation of CRP as a prognostic biomarker for mRCC in clinical practice.

PURPOSE Pembrolizumab, a programmed death 1 inhibitor, demonstrated promising single-agent activity in untreated patients with various cancer types. The phase II KEYNOTE-427 study evaluated efficacy and safety of single-agent pembrolizumab in treatment-naive patients with advanced clear cell renal cell carcinoma (ccRCC; cohort A) and advanced non-ccRCC (cohort B). Results of cohort A are reported. METHODS In this open-label, single-arm phase II study, patients with advanced ccRCC received pembrolizumab 200 mg every 3 weeks for ≤ 24 months. The primary end point was objective response rate by RECIST, version 1.1. RESULTS In the total population (N = 110), median time from enrollment to data cutoff was 35.9 (range, 29.5-40.3) months. Objective response rate was 36.4% with four (3.6%) complete responses and 36 (32.7%) partial responses; disease control rate was 58.2% (95% CI, 48.4 to 67.5). Most patients (68.2%) had a decrease in target lesions, including 30.9% with a reduction ≥ 60%. Median duration of response was 18.9 (range, 2.3-37.6+) months; 64.1% of responders had a response ≥ 12 months (Kaplan-Meier). Median progression-free survival was 7.1 months (95% CI, 5.6 to 11.0). Median overall survival was not reached; 12-month and 24-month overall survival rates were 88.2% and 70.8%, respectively. Durable responses were observed across all International Metastatic RCC Database Consortium categories. Grade 3-5 treatment-related adverse events were reported in 30.0% of patients, of which colitis and diarrhea were most frequent. CONCLUSION Single-agent pembrolizumab showed promising antitumor activity as a first-line treatment in patients with advanced ccRCC, with durable responses across International Metastatic RCC Database Consortium categories. Safety and tolerability profile of pembrolizumab monotherapy was comparable to what has been previously described in other tumor types.

5069 Background: KEYNOTE-427 (NCT02853344), an open-label, single-arm, phase 2 study, showed clinical activity of first-line pembro monotherapy in patients (pts) with ccRCC (cohort A). Previous studies in RCC and immune-oncology suggest depth of response may correlate with long-term benefit. Association between depth of response and OS, along with updated efficacy and safety for cohort A of KEYNOTE-427, are presented. Methods: Pts with histologically confirmed ccRCC, measurable disease (RECIST v1.1), and no prior systemic therapy received pembro 200 mg IV Q3W for 2 y or until progressive disease, unacceptable toxicity, or withdrawal. End points: ORR (primary), DOR, and PFS (RECIST v1.1); OS, and safety. Association between depth of response (maximum reduction from baseline in the sum of target lesions) and OS was evaluated using Cox proportional hazards model with target lesion reduction group as time-varying covariate. Results: 110 pts enrolled; median time from enrollment to data cutoff was 23.1 (range, 16.7-27.5) mo. Overall, 38.2% of pts had favorable and 61.2% had intermediate/poor IMDC risk. ORR was 36.4% (95% CI, 27.4-46.1; 3 CRs, 37 PRs); median (range) DOR was not reached (2.3-23.5+ mo); 64.0% had a DOR ≥12 mo. Median PFS was 7.1 mo (95% CI, 5.6-11.0) and median OS was not reached; 18-mo PFS and OS rates were 26.6% and 80.0%, respectively. 69.1% had some reduction in target lesions. Pts with > 60% reduction in target lesions had a greater probability of survival than pts with a ≤60% reduction (Table). ORR observed in IMDC favorable and intermediate/poor risk was 31.0% and 39.7%, respectively; 18-mo OS rate was 95.2% for favorable and 70.5% for intermediate/poor IMDC risk. Treatment-related AEs (TRAEs) occurred in 81.8% of pts, primarily fatigue (29.1%) and pruritus (28.2%). Grade ≥3 TRAEs occurred in 29.1% of pts; 1 pt died of treatment-related pneumonitis. Conclusions: First-line pembro monotherapy was tolerable and showed promising antitumor activity in advanced ccRCC. In general, pts who had greater reductions in target lesions demonstrated a trend toward improved OS; pts with reduction of tumor burden ≥80% had comparable long term outcomes to those who achieved a RECIST 1.1 defined CR. Clinical trial information: NCT02853344 . [Table: see text]

Testicular cancer is the most common malignancy in young adult men. The prognosis is excellent in limited disease and cure is possible even in advanced disease. Quality performance indicators (QPI) are used in many developed countries as a measure of healthcare performance. We report and discuss the development of a national set of QPIs in Scotland for testicular cancer as a method of gathering demographic data and driving improvement in nationwide testicular cancer outcomes.

309 Background: The KEYNOTE 426 trial demonstrated pem 200mg plus axi twice daily (bd) is effective in aRCC. Pharmacokinetic modelling of pem 400 mg every six weeks demonstrated similar observed exposures to pem 200 mg every three weeks. In NHS Scotland, pem6w + axi was used during the COVID-19 pandemic to reduce hospital visits and for pts’ convenience. Here, we evaluate the RWE of pem6w + axi in aRCC. Methods: Electronic medical records of pts on pem6w + axi between 1 May 2020 & 1 Jun 2021 in two large cancer centers in Scotland were analyzed retrospectively for pts’ characteristics, treatment related adverse events (TRAE) and efficacy. Results: Total of 93 pts were identified (Table). At data cut off of 8 Sep 2021, with a median follow-up of 7 months (mo) (inter-quartile range (IQR) 5 mo; range 0-15 mo), 73 pts (78%) were alive. Clinician assessed radiological response was evaluable in 87 pts. Overall response rate (ORR) including partial response + complete response was noted in 49 pts (56%) with median time to response of 80 days (d). Clinical benefit rate including pts with ORR and stable disease was seen in 72 pts (83%). At data cut off, 24 pts (26%) had progressed with a median time to progression of 117 d (IQR: 85d). Median overall and progression free survival were not reached and follow-up continues. 81 pts (87%) had any grade and 28 pts (30%) had grade 3/4 TRAE. Immune related AE (irAE) of any grade occurred in 60 pts (65%) and grade 3/4 in 19 pts (20%). Common grade 3/4 irAE were transaminitis (10%), colitis (8%), nephritis (2%) and skin (2%). 28 (30%) and 14 pts (15%) respectively required steroids and hospitalisation for irAE with median hospital stay 6 d (range: 2-43 d). 10 pts suffered a second irAE requiring steroids and 5 pts had a second hospital stay with median hospital stay of 6 d. Any grade AE and grade 3/4 AE related to axi occurred in 67 (72%) and 14 pts (15%) respectively. Axi dose was escalated from 5mg to 7mg bd in 12 pts (13%), reduced to 3mg bd in 35 pts (38%) and 2mg bd in 10 pts (11%). 21pts (23%) on Pem and 15pts (16%) on axi discontinued treatment due to TRAE. Conclusions: Our RWE demonstrates that pem6w + axi appears to have comparable safety profile to pem 200mg + axi reported in Keynote 426 study, with the added benefits of less frequent hospital visits. Further follow up continues for efficacy in this heterogeneous pts population. Pt characteristics, total=93 (%).[Table: see text]

350 Background: The role of cytoreductive nephrectomy (CNx) in patients with metastatic renal cell carcinoma (mRCC) is currently in question. Assessing the benefits and risks of CNx is challenging, with a lack of validated prognostic tools. Biomarkers of the systemic inflammatory response have prognostic utility in mRCC and are included in the IMDC score used to predict survival in patients with mRCC treated with systemic therapy. We sought to investigate their role in patients with mRCC who had undergone CNx. Methods: A cohort of 68 patients, suitable for first-line VEGFR inhibitor (VEGFRi) systemic therapy, who had undergone CNx for mRCC, were identified from a clinical database of patients referred to a regional mRCC service. Inflammatory biomarkers from routine blood tests (haemoglobin, white cell count, neutrophil count, platelets, C-reactive protein (CRP), albumin) and the IMDC score, measured at the time of diagnosis of mRCC, were recorded. The relationship between these and overall survival and time to VEGFRi (tVEGFRi) was examined using Kaplan-Meier and Cox-regression methods. Results: Data were available for 68 patients. Median survival was 33.7 months. On multivariate analysis, albumin ( < 35g g/dL v ≥35 g/dL) and CRP (≤ 10 mg/L v > 10 mg/L) were independently associated with overall survival (p = 0.027 and p = 0.034 respectively). Albumin stratified survival from 24.7 to 87.2 months (p < 0.0001) and CRP from 29.4 to 82.3 months (p = 0.004). 40 (59%) patients subsequently commenced VEGFRi therapy. Median tVEGFRi was 18.1 months, with only 5 (7%) patients commencing treatment within 3 months. 16 (24%) patients yet to receive systemic therapy remain alive after a median 54.0 months follow-up. On multivariate analysis, albumin was also predictive of tVEGFRi (p = 0.037), stratifying tVEGFRi from 6.07 to 45.7 months (p = 0.002). Conclusions: These results highlight that biomarkers of the systemic inflammatory response are strong prognostic factors in mRCC patients who have undergone CNx. Albumin and CRP, but not IMDC, predict survival in this patient group. Significantly, the population investigated here differ from those included in the CARMENA and SURTIME studies, with a majority undergoing surveillance prior to VEGFRi therapy. Our results support a role for CNx in patients where deferred systemic therapy strategies may be employed. Albumin may assist in clinical decision making when considering when to start systemic therapy. We advocate further studies to investigate the prognostic role of these simple, routine clinical tests in patients with mRCC undergoing CNx.

348 Background: A subset of patients with metastatic renal cell carcinoma (mRCC) follow an indolent disease course. Given the toxicity and non-curative nature associated with systemic anti-cancer therapy (SACT), some patients may benefit from initial active surveillance (AS). However, selecting patients suitable for this approach is challenging. Biomarkers of systemic inflammation predict survival in mRCC, both independently and as part of the International Metastatic Database Consortium (IMDC) risk score. We sought to use these biomarkers to characterise the time to initiation of SACT (tSACT) in mRCC patients on AS. Methods: 126 mRCC patients clinically assessed and commenced on AS prior to any systemic therapy were retrospectively identified from a regional mRCC clinical database. Patients who underwent metastasectomy for oligometastatic disease at any time were excluded. The primary endpoint, tSACT, was defined as the time from radiological diagnosis of mRCC until SACT initiation, or death, or censorship if continuing AS at follow-up date. Inflammatory biomarkers from routine blood tests (haemoglobin, white cell count, neutrophil count, platelets, C-reactive protein (CRP), albumin) and the IMDC score, measured at the time of diagnosis of mRCC, were recorded. The relationship between these and tSACT was examined using Kaplan-Meier and Cox-regression methods. Results: 66 (52%) patients had commenced SACT. 17 (13.5%) had died without commencing SACT (median survival of the 17 was 40.4 months, range 9.1-130.2 months, and comorbidities may have affected fitness for starting therapy or led to all-cause mortality). 43 patients remained on AS, with minimum and median follow-up of 12.6 months and 39.6 months respectively. The median tSACT was 17.2 months (IQR 8.8-34.8 months). On univariate analysis, CRP and albumin were predictive of time on AS ( p= 0.01 and p= 0.049 respectively). On multivariate analysis, only CRP was independently associated with tSACT ( p= 0.035), stratifying tSACT from 9.1 months (CRP > 10) to 20.9 months (CRP≤10) ( p= 0.009). 111 (88.1%) patients were IMDC 0-1, while 12 (9.5%) and 3 (2.4%) were IMDC 2 or 3 and may have had comorbidities that influenced the initial AS decision. In our cohort the IMDC risk score did not predict time on AS. Conclusions: These results highlight that some patients with mRCC may undergo active surveillance for a marked time period before SACT initiation. We identify routine biomarkers of the systemic inflammatory response that predict time to systemic therapy. In particular CRP, a simple measure of inflammation, stratifies the time to initiation of SACT across a clinically significant time period. This simple, widely available test may help to objectively inform clinical decisions about AS in patients in mRCC. Additional experience is necessary to further define the risks and benefits of this approach.

275 Background: Venous tumor thrombus (VTT) extension occurs in 4-15% cases of renal cell cancer (RCC). The Mayo classification distinguishes 4 levels of VTT extension between the renal vein and supradiaphragmatic inferior vena cava (IVC). Although surgery is performed with curative intent, mortality is high (5-15%) with complications increasing with the level of the VTT. 5-year survival rates are poor; ~40-65% in non-metastatic RCC. It is hypothesised that neoadjuvant targeted therapy could downstage the VTT reducing the extent of surgery, leading to reduced surgical morbidity and mortality, and increased survival. However, level I or II evidence is lacking. NAXIVA provides the first level II evidence in this patient group, assessing the response of VTT to axitinib. Extensive translational sampling will provide in depth interrogation of VTT (using genomics, proteomics, immunophenotyping and metabolomics) to examine the role of the tumor microenvironment of VTT and response to axitinib. Methods: NAXIVA was a single arm, single agent, multi-center phase 2 feasibility study of axitinib in patients with both metastatic and non-metastatic clear cell RCC prior to nephrectomy and thrombectomy. A Simon two stage minimax design was adopted and the trial designed for adequate power to distinguish a 25% improvement in the Mayo VTT level. 21 patients were recruited over a 24 month period between 15/Dec/2017 and 06/Jan/2020 at 5 sites across the UK. Patients were treated with 8 weeks of axitinib (starting dose 5mg bd, increasing to 10mg bd as tolerated) prior to planned surgery. The primary endpoint was the percentage of evaluable patients with an improvement in VTT according to the Mayo classification (assessed using MRI abdomen scans at screening and week 9, prior to surgery. Secondary endpoints were percentage change in surgical approach, percentage change in VTT height, response rate (by RECIST) and evaluation of surgical morbidity assessed by Clavien-Dindo classification. Results: The percentage of evaluable patients with an improvement in VTT according to the Mayo classification was 26.58% [80% CI: 15.76%, 39.74%] (6 of 21 evaluable patients). 35.29% (6 of 17 patients who progressed to surgery) had a change in surgical approach to a less invasive option. There was a median percentage reduction in VTT height of 21.49% (SD=27.60%). The response rate (by RECIST) in the evaluable population was 61.90% SD, 14.29% PR, 9.52% PD. In terms of surgical morbidity 11.76% (2 of 17 patients who progressed to surgery) experienced a Clavien-Dindo 3 or greater complication (0 CD3, 1 CD4, 1 CD5). Conclusions: NAXIVA provides unique prospective data on the feasibility of neoadjuvant axitinib administration to down stage IVC VTT and reduce the extent of surgery. Work is ongoing to establish predictors of response. Clinical trial information: NCT03494816 .

5034 Background: KEYNOTE-427 (NCT02853344), a single-arm, open-label, phase 2 study, showed antitumor activity with first-line pembro monotherapy in nccRCC (cohort B). Studies of RCC and immune-oncology have shown that depth of tumor response may correlate with long-term benefit. We present the association between depth of response and OS plus updated efficacy and safety data in cohort B. Methods: Pts with histologically confirmed nccRCC, who did not receive prior systemic therapy, and who have measurable disease (RECIST v1.1) received pembro 200 mg IV Q3W for 2 y or until progressive disease, unacceptable toxicity, or withdrawal. End points were ORR (primary), DOR, and PFS (RECIST v1.1); OS; and safety. Association between depth of response, defined as maximum reduction from baseline in sum of target lesions, and OS was evaluated using a Cox proportional hazards model with target lesion reduction group as time-varying covariate. Results: Of 165 pts, 72% had papillary histology, 13% had chromophobe histology, and 16% were unclassified. Median time from enrollment to data cutoff was 18.7 mo (range, 9.9-26.0). ORR was 26.1% (95% CI, 19.5-33.5; 10 CRs, 33 PRs). Median (range) DOR was 15.3 mo (2.8-21.0+); 57.3% had DOR ≥12 mo. At 18-mo, PFS rate was 18.9% and OS rate was 67.0%. Most pts (58.8%) had some reduction in target lesions. Pts with a > 30% reduction in target lesions had an increased probability of survival (Table). ORR (95% CI) was similar for papillary (28.0% [20.1-37.0]) and unclassified (30.8% [14.3-51.8]) histology but lower for chromophobe (9.5% [1.2-30.4]). OS rates at 18 mo were 70.8%, 66.7%, and 50.0 in the papillary, chromophobe, and unclassified groups, respectively. Treatment-related AEs (TRAEs) occurred in 67.9% of all pts, primarily pruritus (19%), hypothyroidism (14%), and fatigue (14%). Grade 3-5 TRAEs occurred in 14% of pts; 2 pts died of TRAEs (pneumonia and cardiac arrest). Conclusions: First-line pembro monotherapy continued to show antitumor activity in nccRCC with no new safety concerns. In general, for pts who had greater reductions in target lesions, the trend was toward improved OS; pts with reduction of tumor burden ≥80% had comparable long term outcomes to those who achieved a RECIST 1.1 defined CR. Clinical trial information: NCT02853344 . [Table: see text]

5024 Background: We assessed the association of baseline RNA-sequencing–based gene expression signatures and DNA alterations with response or resistance to pembrolizumab in patients with advanced renal cell carcinoma in cohorts A (clear cell; n = 110) and B (non-clear cell; n = 165) of the phase 2 KEYNOTE-427 study (NCT02853344). Methods: Using RNA-sequencing, we analyzed the association of gene expression signatures (18-gene T-cell–inflamed gene expression profile [GEP]; 10 non–T-cell–inflamed GEP canonical signatures [angiogenesis, gMDSC, glycolysis, hypoxia, mMDSC, MYC, proliferation, RAS, stromal/EMT/TGFβ, WNT]) quantifying tumor microenvironment elements (TME) with objective response rate (ORR) and progression-free survival (PFS). Canonical signatures were derived from 2 databases (TCGA, Moffit) using an algorithm that included genes based on their correlation to reference signatures in the literature. Signature definitions were finalized before linking to the clinical data, and significance was prespecified at 0.10 given the potential for limited power. Canonical signatures were analyzed through regression testing of response for association with consensus signatures after adjusting for T-cell–inflamed GEP and International Metastatic RCC Database Consortium scores in the model. P values were adjusted for multiplicity. Using whole exome sequencing, we also summarized the association of renal cell carcinoma driver gene mutations with ORR. Clinical data cutoff: Jan 30, 2019. Results: Patient characteristics for this analysis were comparable to the overall population. In cohort A, T-cell–inflamed GEP (n = 78) was statistically significantly associated with a better ORR ( P = 0.021; AUROC = 0.65) but not PFS ( P = 0.116). No other TME canonical signatures showed a correlation with ORR or PFS. ORR was estimated for mutations (Table). Conclusions: RNA-sequencing–based, T-cell–inflamed GEP was associated with ORR in patients with clear cell renal cell carcinoma receiving first-line pembrolizumab. Precision was limited by sample size for estimating ORR by specific gene mutation status. Evaluation of tissue-based biomarkers in larger studies are planned. Biomarker analyses from patients in cohort B will also be presented. Clinical trial information: NCT02853344 . [Table: see text]

729 Background: We evaluated the association (assoc) of baseline RNA-seq–based signatures with response/resistance to pembro from the phase 2 KEYNOTE-427 study (NCT02853344) in pts with advanced clear cell RCC enrolled in cohort A (n = 110). Methods: In pembro-treated pts with RNA-seq and clinical data (N = 78), we analyzed the assoc of signatures (18-gene tumor T-cell–inflamed GEP; 10 non–T-cell–inflamed GEP canonical signatures [angiogenesis, gMDSC, glycolysis, hypoxia, mMDSC, MYC, proliferation, RAS, stromal/EMT/TGFβ, WNT]) quantifying the TME with clinical outcomes. Canonical signatures were derived from 2 databases (TCGA, Moffit) using an algorithm that included genes based on their correlation to reference signatures in the literature. Signature definitions were finalized before linking to the clinical data, and significance was prespecified at 0.10 given the potential for limited power. Canonical signatures were also analyzed through regression testing of response and the residuals of consensus signatures after adjusting for T-cell–inflamed GEP and IMDC scores in the model. P values were adjusted for multiplicity. Database cutoff date for clinical data: March 12, 2019. Results: Pt characteristics for this analysis were similar to those of the overall cohort A population. T-cell–inflamed GEP was statistically significantly assoc with ORR ( P = 0.021) but not PFS ( P = 0.116). When adjusting for PD-L1 expression (CPS by IHC) and IMDC scores, T-cell–inflamed GEP remained statistically significantly assoc with ORR ( P = 0.059). The angiogenesis signature was not assoc with response. PD-L2 RNA-seq expression was not assoc with response with multiplicity-adjusted P values. Like PD-L1 IHC, PD-L2 RNA-seq expression moderately correlated with T-cell–inflamed GEP and did not show independent predictive value when adjusted for T-cell–inflamed GEP and IMDC scores. Conclusions: RNA-seq–based, T-cell–inflamed GEP was assoc with ORR in pts with clear cell RCC receiving first-line pembro monotherapy; no canonical signatures showed statistical significance. Future directions for these data include whole exome sequencing analysis. Clinical trial information: NCT02853344.

Background KEYNOTE-427 (NCT02853344) is a single-arm, open-label, phase 2 study of pembro monotherapy in patients (pts) with advanced clear cell RCC (cohort A) and nccRCC (cohort B). Updated cohort B results with additional follow-up are presented. Methods 165 pts with histologically confirmed nccRCC, no prior systemic therapy, and measurable disease (RECIST v1.1) enrolled. Pts received pembro 200 mg IV Q3W for 35 cycles (∼2 y) or until progressive disease, unacceptable toxicity, or withdrawal. Primary end point: objective response rate (ORR, RECIST v1.1 by blinded independent central review). Additional end points: duration of response (DOR), PFS, OS, data by sarcomatoid differentiation, histology, and PD-L1 expression (combined positive score [CPS] ≥1 for PD-L1+). Results Histology by central pathology review: papillary 72% (n = 118), chromophobe 13% (n = 21), unclassified 16% (n = 26); 62% were PD-L1+. Median follow-up: 15.0 mo (range, 0.9-25.4). Overall ORR was 26.1% (95% CI, 19.5-33.5; 10 [6.1%] CR, 33 [20.0%] PR) and median (range) DOR was 15.3 mo (2.8-21.0+). For responders, 57.3% had a response ≥12 mo. 12-mo PFS and OS rates were 24.7% and 73.7%, respectively. ORR (95% CI) was 28.0% (20.1-37.0) in papillary, 9.5% (1.2-30.4) in chromophobe, and 30.8% (14.3-51.8) in unclassified nccRCC; for responders, 55.4%, 50.0%, and 71.4% in the papillary, chromophobe and unclassified groups had a response ≥12 mo. Median (range) DOR was not reached in the unclassified and was 15.3 mo (2.8-21.0+) for the papillary group. ORR (95% CI) was 42.1% (26.3-59.2) for pts with sarcomatoid differentiation (n = 38). ORR (95% CI) in pts with CPS≥1 and CPS Conclusions Single-agent pembro continued to show encouraging antitumor activity in nccRCC, especially with papillary or unclassified histology and CPS≥1. Safety profile of pembro was as expected. Clinical trial identification NCT02853344, August 2, 2016. Editorial acknowledgement Matthew Grzywacz, PhD, of the ApotheCom pembrolizumab team (Yardley, PA, USA), funded by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Legal entity responsible for the study Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Funding Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Disclosure C. Suarez: Advisory / Consultancy: Astellas, BMS, Eusa, Ipsen, Novartis, Pfizer, Sanofi-Aventis; Research grant / Funding (self): Ipsen; Speaker Bureau / Expert testimony: AstraZeneca, BMS, Ipsen, Pfizer; Travel / Accommodation / Expenses: Roche, Pfizer, Ipsen; Research grant / Funding (institution): AB Science, Aragon Pharmaceuticals, Arog Pharmaceuticals, INC, Astellas Pharma., AstraZeneca AB, Aveo Pharmaceuticals INC, Bayer AG, Blueprint Medicines Corporation, BN Immunotherapeutics INC, Boehringer Ingelheim Espana, S.A., Bristol-Myers Squibb Intern; Non-remunerated activity/ies: Roche Steering Committee. J. Lee: Honoraria (self): Novartis Korea, BMS Korea; Advisory / Consultancy: Pfizer Korea, Janssen, Sanofi Aventis, Astellas Korea, BMS Korea, Ipsen Korea; Leadership role: Korea Cancer Study Group. M. Ziobro: Advisory / Consultancy, Travel / Accommodation / Expenses: Bristol-Myers Squibb; Advisory / Consultancy: MSD; Advisory / Consultancy, Travel / Accommodation / Expenses: Roche; Advisory / Consultancy: Novartis. V.B. Matveev: Honoraria (self), Advisory / Consultancy: Bayer; Honoraria (self), Advisory / Consultancy: Bristol-Myers Squibb; Honoraria (self), Advisory / Consultancy: Janssen; Honoraria (self), Advisory / Consultancy: Astellas. F. Donskov: Honoraria (institution): Pfizer; Honoraria (institution): Ipsen. F. Pouliot: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony: Amgen; Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): Astellas; Honoraria (self), Honoraria (institution), Advisory / Consultancy: Janssen; Honoraria (self), Honoraria (institution), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution), Travel / Accommodation / Expenses: Sanofi; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution), Travel / Accommodation / Expenses: Bayer; Advisory / Consultancy: Progenics. B.Y. Alekseev: Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: Astellas; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: AstraZeneca; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: Bayer; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: BMS; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: Ferring; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: Janssen; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: MSD; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: Pfizer; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: Roche; Honoraria (self), Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (self), Research grant / Funding (institution), Travel / Accommodation / Expenses: Sanofi. P.J. Wiechno: Honoraria (self): Bayer; Honoraria (self): BMS; Honoraria (self), Travel / Accommodation / Expenses: Pfizer; Honoraria (self): Astellas; Honoraria (self): Ipsen; Honoraria (self): Janssen-Cilag; Honoraria (self): Novartis. M.A. Climent: Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: MSD; Honoraria (self), Advisory / Consultancy: BMS; Honoraria (self), Advisory / Consultancy: Roche; Advisory / Consultancy: Pierre Fabre; Honoraria (self), Advisory / Consultancy: Pfizer. R. Kloss Silverman: Full / Part-time employment: Merck & Co., Inc. R.F. Perini: Shareholder / Stockholder / Stock options, Full / Part-time employment: Merck & Co., Inc. C. Schloss: Shareholder / Stockholder / Stock options, Full / Part-time employment: Merck & Co., Inc. D.F. McDermott: Honoraria (self), Research grant / Funding (self): BMS; Honoraria (self), Research grant / Funding (self): Pfizer; Honoraria (self), Research grant / Funding (self): Merck; Honoraria (self), Research grant / Funding (self): Novartis; Honoraria (self), Research grant / Funding (self): Exelixis; Honoraria (self): Array BioPharm; Honoraria (self), Research grant / Funding (self): Genentech BioOncology; Honoraria (self), Research grant / Funding (self): Alkermes, Inc.; Honoraria (self): Jounce Therapeutics; Honoraria (self), Research grant / Funding (self): X4 Pharma; Honoraria (self), Research grant / Funding (self): Peloton Therapeutics; Honoraria (self): EMD Serono; Honoraria (self): Eli Lilly and Company; Research grant / Funding (self): Prometheus Laboratories. M.B. Atkins: Advisory / Consultancy, Research grant / Funding (self): Merck; Advisory / Consultancy, Research grant / Funding (self): Novartis; Advisory / Consultancy, Research grant / Funding (self): Genentech/Roche; Advisory / Consultancy: Pfizer; Advisory / Consultancy: Exelixis; Advisory / Consultancy: Eisai; Advisory / Consultancy: AstraZeneca; Advisory / Consultancy: Array; Advisory / Consultancy, Research grant / Funding (self): BMS. All other authors have declared no conflicts of interest.

4570 Background: KEYNOTE-427 (NCT02853344) is an open-label, single-arm, phase 2 study to evaluate efficacy and safety of first-line single-agent pembro, a programmed death 1 (PD-1) inhibitor, in patients (pts) with ccRCC (cohort A) and non–clear cell RCC (cohort B). Updated follow up from cohort A are presented. Methods: Pts with histologically confirmed ccRCC, measurable per RECIST v1.1, and no prior systemic therapy were eligible. Pts received pembro 200 mg IV Q3W for 2 y or until confirmed progressive disease, unacceptable toxicity, or pt decision to withdraw. Primary end point was objective response rate (ORR; per RECIST v1.1 blinded independent central review). Additional end points included duration of response (DOR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and safety. Results: 110 pts enrolled; median (range) follow-up was 18.0 (2.5-22.7) mo. Median age (range) was 64 (29-87); 38.2%, 47.3%, and 14.5% had favorable, intermediate, and poor IMDC risk, respectively; 47.3% were PD-L1 positive. Confirmed ORR was 36.4% with 3 (2.7%) CRs and 37 (33.6%) PRs. Median DOR was not reached. Median PFS was 7.1 mo (95% CI, 5.6-11.0) and median OS was not reached. Results by IMDC category are outlined in the table. By PD-L1 status, confirmed ORR was 44.2% and 29.3% for positive and negative, respectively. By sarcomatoid differentiation (n=11), confirmed ORR was 63.6%. Treatment-related AEs occurred in 80.9%, with pruritus (28.2%) and fatigue (28.2%) most commonly reported. One pt died of treatment-related pneumonitis. Conclusions: With a median 18-months’ follow up, first-line pembro monotherapy continued to show antitumor activity in pts with ccRCC. Meaningful responses were observed in pts with intermediate/poor IMDC risk, PD-L1 positive and sarcomatoid differentiated tumors. Safety profile was comparable to previously reported. Clinical trial information: NCT02853344. [Table: see text]

Objective To report the outcomes of >1000 men with low-risk prostate cancer treated with low-dose-rate (LDR) brachytherapy at three large UK cancer centres. Patients and Methods A total of 1038 patients with low-risk prostate cancer (prostate-specific antigen [PSA] ≤10 ng/mL, Gleason score 6, ≤T2b disease) were treated with LDR iodine 125 (I-125) brachytherapy between 2002 and 2007. Patients were treated at three UK centres. PSA and clinical follow-up was performed at each centre. Biochemical recurrence-free survival was reported for the cohort. Results The median (range) PSA follow-up for the whole group was 5 years (4 months to 9 years). A total of 79 patients had biochemical failure, defined by a rise in PSA level: 16 patients fulfilled the ASTRO definition of biochemical failure, 25 patients fulfilled the Phoenix definition and 38 patients fulfilled both definitions. The 5-year biochemical relapse-free survival (bRFS) rate was 94.1% by the ASTRO definition and 94.2% by the Phoenix definition. The absence of neoadjuvant hormone therapy was predictive of inferior biochemical control as defined by the Phoenix definition (P = 0.033). Conclusions Our prospective multicentre series showed excellent bRFS with LDR I-125 brachytherapy for patients with low-risk prostate cancer. Further work is necessary to define the role of neoadjuvant androgen deprivation therapy in combination with brachytherapy.

4500Background: Programmed death-1 (PD-1) inhibitor–based combination therapy shows clinical benefit in first-line accRCC. However, data are limited on clinical impact of first-line PD-1 inhibitor ...

Introduction: This Centre has previously reported outcomes for patients treated with neoadjuvant hormone therapy (NAHT) and 52.5Gy in 20 fractions. We now present the outcome data for patients treated with 55Gy in 20 fractions and NAHT. Methods and Materials: 584 patients were treated for T1-T3 node negative prostate cancer. The median age was 67.2 years (range 49-80). All patients received 3 months of NAHT followed by CT planned conformal radiotherapy to the prostate using 55Gy in 20 fractions. 147 patients considered at particularly high risk of relapse also received 2 years of adjuvant androgen deprivation. Outcomes were obtained through serial PSA measurement. Patients were classified into prognostic groups according to Zelefsky criteria. PSA relapse was defined according to Houston criteria. The outcomes with 55Gy were compared with the 52.5Gy cohort. Results: The 10 year cause specific survival increased from 67.3% with 52.5Gy to 92.9% in the 55Gy group. Patients receiving 55Gy had better outcomes than those receiving 52.5Gy in all prognostic groups with or without adjuvant hormone use. PSA relapse free survival at five years in the patients who did not receive adjuvant hormones are:- 80.2 v 63.6% in the ‘Good’, 69.5 v 43.7% in the ‘Intermediate’ and 40.3 v 15.3% in the ‘Poor’ prognostic groups (p

Aims High dose rate (HDR) brachytherapy offers a highly conformal approach to radiotherapy delivery, enabling dose escalation. We report our experience using a combined HDR boost and external beam radiotherapy (EBRT) approach and its associated toxicity and effect on quality of life. Materials and methods Patients with intermediate- or high-risk prostate cancer were treated with a single fraction HDR boost and EBRT between July 2008 and March 2010. Patient-reported toxicity data were collected at baseline and regular intervals after radiotherapy using International Prostate Symptom Score and Late Effects in Normal Tissues-Subjective, Objective, Management and Analytic scales (LENT-SOMA) questionnaires; health-related quality of life data were captured by the Expanded Prostate Cancer Index Composite (EPIC) questionnaire. Results Ninety-five patients received an HDR boost of 12.5 Gy followed by EBRT delivered as 37.5 Gy in 15 fractions over 3 weeks. The International Prostate Symptom Score peaked 6 weeks after radiotherapy (median value: 9). The LENT-SOMA bladder/urethra mean baseline score was 0.35 and peaked 6 weeks after radiotherapy (mean = 0.59). Difficulties with urinary flow and frequency were the most common reported symptoms. LENT-SOMA rectum/bowel mean scores at baseline were 0.24 and peaked after 6 months (mean = 0.37). Bowel urgency was the most common reported toxicity. EPIC urinary scores returned to baseline values at 6 months and bowel median scores recovered after 24 months. There were no statistically significant associations between patient or dosimetric parameters and patient-reported outcomes. Conclusion A combined HDR boost and hypofractionated EBRT regimen offers a well-tolerated method of dose escalation with acceptable levels of patient-reported toxicity.

To report the outcomes of1000 men with low-risk prostate cancer treated with low-dose-rate (LDR) brachytherapy at three large UK cancer centres.A total of 1038 patients with low-risk prostate cancer (prostate-specific antigen [PSA] ≤10 ng/mL, Gleason score 6, ≤T2b disease) were treated with LDR iodine 125 (I-125) brachytherapy between 2002 and 2007. Patients were treated at three UK centres. PSA and clinical follow-up was performed at each centre. Biochemical recurrence-free survival was reported for the cohort.The median (range) PSA follow-up for the whole group was 5 years (4 months to 9 years). A total of 79 patients had biochemical failure, defined by a rise in PSA level: 16 patients fulfilled the ASTRO definition of biochemical failure, 25 patients fulfilled the Phoenix definition and 38 patients fulfilled both definitions. The 5-year biochemical relapse-free survival (bRFS) rate was 94.1% by the ASTRO definition and 94.2% by the Phoenix definition. The absence of neoadjuvant hormone therapy was predictive of inferior biochemical control as defined by the Phoenix definition (P = 0.033).Our prospective multicentre series showed excellent bRFS with LDR I-125 brachytherapy for patients with low-risk prostate cancer. Further work is necessary to define the role of neoadjuvant androgen deprivation therapy in combination with brachytherapy.

Kilovoltage cone-beam CT (kV CBCT) can be acquired during the delivery of volumetric modulated arc therapy (VMAT), in order to obtain an image of the patient during treatment. However, the quality of such CBCTs is degraded by megavoltage (MV) scatter from the treatment beam onto the imaging panel. The objective of this paper is to introduce a novel MV scatter correction method for simultaneous CBCT during VMAT, and to investigate its effectiveness when compared to other techniques. The correction requires the acquisition of a separate set of images taken during VMAT delivery, while the kV beam is off. These images - which contain only the MV scatter contribution on the imaging panel - are then used to correct the corresponding kV/MV projections. To test this method, CBCTs were taken of an image quality phantom during VMAT delivery and measurements of contrast to noise ratio were made. Additionally, the correction was applied to the datasets of three VMAT prostate patients, who also received simultaneous CBCTs. The clinical image quality was assessed using a validated scoring system, comparing standard CBCTs to the uncorrected simultaneous CBCTs and a variety of correction methods. Results show that the correction is able to recover some of the low and high-contrast signal to noise ratio lost due to MV scatter. From the patient study, the corrected CBCT scored significantly higher than the uncorrected images in terms of the ability to identify the boundary between the prostate and surrounding soft tissue. In summary, a simple MV scatter correction method has been developed and, using both phantom and patient data, is shown to improve the image quality of simultaneous CBCTs taken during VMAT delivery. © 2012 Institute of Physics and Engineering in Medicine.

e16069 Background: Docetaxel plus prednisolone is an established treatment for men with advanced prostate cancer. Clinicians need to be able to identify men who are not benefiting from chemotherapy, and a key unanswered question is how many cycles of docetaxel should men receive before this assessment is made. We investigated the prognostic significance of a PSA response to docetaxel chemotherapy and the number of cycles after which an absence of PSA response could reliably predict future non-response. Methods: Data was collected for men who received one to ten cycles of docetaxel for castrate refractory prostate cancer between 2005 and 2011. PSA was monitored during treatment. All men were treated at a single centre, The Christie NHS Foundation Trust, UK. Survival is defined as the interval between the first dose of docetaxel and the date of death. Results: Data was available for 320 patients. At the commencement of chemotherapy, median age was 67 years (range 49-81yrs) and median PSA was 207ng/ml. All patients had a Karnofsky Performance Status ≥ 70%. There were 239 deaths and the median survival of the whole group was 403 days. 140 (44%) patients received 6 cycles of docetaxel and 23 patients (7%) received 10 cycles. Median survival was significantly longer in men who had any fall in PSA during chemotherapy compared to those whose PSA did not fall (462 days vs 268 days, p